This campaign was from 1 December 1971 to 29 March 1972.. The U.S. continued to reduce its ground presence in South Vietnam during late 1971 and early 1972, but American air attacks increased while both sides exchanged peace proposals.
In early January 1972 President Nixon confirmed that U.S. troop withdrawals would continue but promised that a force of 25,000-30,000 would remain in Vietnam until all American prisoners of war were released. Secretary of Defense Laird reported that Vietnamization was progressing well and that U.S. troops would not be reintroduced into Vietnam even in a military emergency. U.S. troop strength in Vietnam dropped to 136,500 by 31 January 1972, to 119,600 by 29 February, and then to 95,500 by the end of March.
During the last week of December 1971 U.S. Air Force and Navy planes carried out 1,000 strikes on North Vietnam, the heaviest U.S. air attacks since November 1968. Allied commanders insisted that it was necessary because of a huge buildup of military supplies in North Vietnam for possible offensive operations against South Vietnam and Cambodia. Stepped up North Vietnamese anti-aircraft and missile attacks on U.S. aircraft that bombed the Ho Chi Minh Trail in Laos also contributed to the decision. During January 1972 American planes maintained their intermittent bombardment of missile sites in North Vietnam and on he Laotian border and also struck North Vietnamese troop concentrations in the Central Highlands of South Vietnam.
On 25 January President Nixon announced an eight part program to end the war which included agreement to remove all U.S. and foreign allied troops from Vietnam no later than six months after a peace agreement was reached. The North Vietnamese and Viet Cong delegates rejected the proposal and insisted upon complete withdrawal of all foreign troops from Indochina and cessation of all forms of U.S. aid to South Vietnam.